The present invention relates to a lane keep support system or lane keeping apparatus for vehicles.
A Japanese Published Patent Application Kokai No. H11(1999)-96497 discloses a lane keep system for keeping a controlled vehicle in a lane of a road. This system is arranged to hold a running course of the controlled vehicle within a lane by calculating a side deviation of a running position of the controlled vehicle from a reference position in the lane, by using this side deviation to calculate a steering control torque of a magnitude which a driver can readily overcome, and by producing an actual steering torque in a direction to reduce the side deviation to achieve the calculated steering control torque with a steering actuator.
It is an object of the present invention to provide a lane keeping apparatus and/or method capable of producing a steering torque for lane keeping with a smaller steering actuator.
According to the present invention, a lane keeping apparatus comprises: an automatic steering section comprising a steering actuator to reduce a deviation of an actual wheel steer angle of a controlled vehicle from a calculated target wheel steer angle for lane keeping; and a steering characteristic adjusting section to adjust a steering characteristic of the controlled vehicle in the case of an automatic steering mode of the automatic steering section, in a first direction to improve a yawing response of the controlled vehicle or in a second direction to improve a running stability of the controlled vehicle in accordance with a steering amount of the automatic steering section.
A lane keeping apparatus according to the invention may comprise: automatic steering means for calculating a target wheel steer angle for lane keeping and for controlling a steering actuator to bring an actual wheel steer angle of a controlled vehicle to the target wheel steer angle; and steering characteristic adjusting means for adjusting a steering characteristic of the controlled vehicle in the case of an automatic steering mode of the automatic steering means, in accordance with a parameter, such as the target wheel steer angle, representing a steering amount of the automatic steering means in one of the first and second directions.
A lane keep control method according to illustrated embodiments of the present invention comprises: calculating a target wheel steer angle to achieve an automatic steering control for lane keeping: determining a modification quantity to adjust a steering characteristic of the controlled vehicle in accordance with a parameter representing a steering amount of the automatic steering control; and controlling an actual wheel steer angle of the controlled vehicle so as to bring the actual wheel steer angle to the target wheel steer angle, and adjusting the steering characteristic of the controlled vehicle in accordance with the modification quantity in one of a first direction to improve a yawing response of the controlled vehicle and a second direction to improve a running stability of the controlled vehicle.
A vehicle according to illustrated embodiments of the invention comprises: a first actuating system comprising a lane keeping automatic steering actuator to vary a first manipulated variable to bring an actual wheel steer angle of the vehicle to a target wheel steer angle calculated for lane keeping; a second actuating system to vary a second manipulated variable affecting a steering characteristic of the vehicle; and a control unit to adjust the steering characteristic of the vehicle by modifying the second manipulated variable in accordance with a steering amount of the first actuating system. The second actuating system may be at least one of a front and rear roll stiffness distribution control system such as an active suspension system or a system capable of varying damping forces of shock absorbers, a front and rear driving force distribution control system, a four wheel steering system, and a differential limiting amount control system.